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Difficulty: MediumClimate Change, Global Warming and Ozone Layer Depletion

Following the successful phase-out of manufactured Chlorofluorocarbons (CFCs) under international environmental agreements, recent atmospheric assessments indicate that a specific compound has emerged as the single largest anthropogenic emission contributing to stratospheric ozone depletion, while also acting as a long-lived greenhouse gas with a 100-year Global Warming Potential nearly 273 times that of carbon dioxide (CO2CO_2). Which chemical compound is responsible for this dual atmospheric impact?

  1. Nitrous oxide (N2ON_2O)Answer
  2. B
    Sulfur hexafluoride (SF6SF_6)
  3. C
    Methane (CH4CH_4)
  4. D
    Carbon tetrachloride (CCl4CCl_4)

Answer

Nitrous oxide (N2ON_2O) is the correct choice because it is currently the most significant anthropogenic ozone-depleting substance emitted globally while also being a major greenhouse gas with a Global Warming Potential nearly 273 times that of CO2CO_2.
Nitrous oxide (N2ON_2O) is released primarily from agricultural soil management, synthetic fertilizers, and industrial processes. In the stratosphere, photolysis converts N2ON_2O into reactive nitric oxide (NONO) radicals, which catalytically destroy ozone. Because N2ON_2O emissions are not restricted under the original Montreal Protocol in the same way as chlorofluorocarbons, it has become the single largest human-emitted ozone-depleting substance while maintaining a high Global Warming Potential (~273).

Step-by-Step Solution

1
Identify the chemical compound acting as both a major greenhouse gas and the leading current anthropogenic driver of stratospheric ozone depletion.
Evaluate compounds regulated under environmental frameworks for dual atmospheric roles.
With CFC emissions drastically reduced under the Montreal Protocol, agricultural and industrial emissions of Nitrous Oxide (N2ON_2O) have become the largest un-phased anthropogenic ozone-depleting emission.
2
Verify atmospheric chemistry mechanisms and radiative forcing properties.
Confirm that N2ON_2O breaks down into nitrogen oxides (NOxNO_x) in the stratosphere, catalytically destroying ozone, and has a 100-year GWP around 273.
This matches both criteria stated in the stem.

Key Concept

Nitrous Oxide dual role in Climate Change and Stratospheric Ozone Depletion
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Topics

Climate Change, Global Warming and Ozone Layer Depletion